Is the end in sight?: campaigners are now talking openly of beating the AIDS epidemic

TARGETS, students of management agree, help achieve goals. The best are demanding but realistic. And that is something those in charge of the fight against AIDS have come to realise. Their latest target, by far their most ambitious, is to end the epidemic by 2030. “End” is an elastic term, since there is no cure for HIV infection, nor is one in sight. But optimists think a combination of the tools available—particularly the antiretroviral (ARV) drugs which now keep around 13m people alive—could be enough to stop the virus spreading. In the parlance of epidemiologists, they believe they can arrive at R0<1. In layman’s terms, that means each infected individual, during the course of his or her lifetime, will pass the infection on to less than one person on average.

That would be a stunning achievement. HIV was unknown to science a mere 33 years ago. A combination of scientific research and political willpower has got the virus on the run. According to calculations by UNAIDS, the United Nations agency created to deal with the disease, 1.5m people died of it last year. That is down from a peak of 2.4m in 2005 (see chart). The rate of new infections has been falling for longer.

To arrive at a point in 2030 where the rate of new infections is negligible is an ambitious aim, but not a foolish one. The tools to achieve it exist, and those at the 20th International AIDS Conference, held this week in Melbourne, are sharpening them. Sadly, though, six delegates on their way to the conference were killed when flight MH17 was shot down over eastern Ukraine on July 17th. One of those delegates was Joep Lange, a former president of the International AIDS Society (see obituary). But their work goes on.

Transmission break:
A study published three years ago showed that treatment as prevention works—at least in the case of cohabiting couples where only one partner is infected. The likelihood of passing on the virus in these circumstances was reduced by 96%. How effective treatment as prevention is in the rough and tumble of wider human life was not so clear at that time, but research published earlier this year by a group at the University of KwaZulu-Natal, in South Africa, shows that uninfected people living in areas where 30-40% of those infected are on ARVs are 38% less likely to succumb than those in places where ARV coverage is less than 10%.As Salim Abdool Karim, head of the Centre for the AIDS Programme of Research, in South Africa, told delegates, many ways are now available to prevent HIV’s transmission—from counselling and condoms to drugs and circumcision (which cuts away a piece of the penis called the foreskin that is rich in cells susceptible to HIV infection). One of the most effective of these is, fortuitously, a side-effect of ARV treatment. This reduces the level of the virus in people’s bodies so much that it stops them infecting others, a phenomenon known as “treatment as prevention”.

Drugs are also emerging as a way for those who think they are at risk to protect themselves. Such “pre-exposure prophylaxis” has been talked of for a long time. It is now actually happening, thanks to the discovery that a medicine called Truvada (a combination of tenofovir and emtricitabine) can be used this way.

Robert Grant of the University of California, San Francisco, who led the original trial of Truvada’s prophylactic powers, told the meeting of follow-up research at 11 sites on four continents. His new study, like his original one, looked mainly at gay men. It confirmed that Truvada does indeed reduce the risk of infection by about 90% and, crucially, that it is not necessary to take it every day. Four times a week will suffice, so the forgetful are not at risk, as was once feared.

That matters, because many gay activists were suspicious that people might take Truvada insufficiently regularly and, at the same time, scale back on other precautions, thus exposing themselves to risk. As a consequence, uptake of the medicine had been low. Now it may increase.

Using a pre-exposure prophylaxis clearly makes sense for the individuals involved and, if widely adopted, would help curb the epidemic. The World Health Organisation estimates that its widespread use by gay men might avert 1m infections over a decade. If heterosexuals adopted it too, that figure could be much larger. But Truvada is expensive (about $1,300 for a month’s course), and even were it cheap, it is not clear how many people actually would use it.

Tools to make a big dent in the epidemic thus exist. But, as the example of Truvada shows, they are not free—and many fear that politicians’ eyes are wandering from AIDS to other things. The Post-2015 Development Agenda, intended to follow on from the United Nations’ Millennium Development Goals, which were set in 2000 and which explicitly mention AIDS as a problem to be dealt with, do not, at the moment, mention the disease directly. This worries many. Spending on prevention and treatment, about $19 billion a year in a combination of locally raised money and foreign aid, is thought unlikely to rise over the next few years. Those fighting AIDS must learn to do more with less.

One watchword here is granularity. The world’s AIDS maps, which once recorded rates only on a country-by-country basis, now do so region by region. This means effort can be focused on the worst-affected places within a country, not just on the worst-affected countries. Deborah Birx, America’s global AIDS co-ordinator, thinks such focus is essential. It will, she believes, keep downward pressure on the infection rate without too much extra expense. A study published in the Lancet on July 19th, to coincide with the conference, supports her in this. Sarah-Jane Anderson of Imperial College London and her colleagues have crunched the numbers for Kenya and concluded that focusing on the worst-affected parts of that country could, over 15 years, reduce the number of new infections by 100,000 at no extra cost.

Going with the grain

Granularity also applies to people. Researchers have long known that gay men, prostitutes and those who inject themselves with drugs are at higher risk than others, and sensible governments have taken this into account when designing their policies. Another set of papers in the latest Lancet excoriate those who do not—particularly those who persecute prostitutes. The authors suggest decriminalising prostitution could avert a third of the infections that would otherwise happen to prostitutes and their customers. But even within the wider population, some people are more at risk than others, and what is going on here is not always clear.

In KwaZulu-Natal, for example, the rate of infection in boys at, or just out of school, rises slowly only as they get older, from 1% in those under 15 to 1.8% in those over 20. In girls, it rises from 2.6% to 24.7%. Dr Karim’s group has tried to find out what is going on by sequencing the virus in infected pupils in a group of five schools, to see who might have passed it on to whom. The answer is that these teenagers are not catching it from each other: few pupils shared viral genotypes. The boys are not catching HIV at a huge rate anywhere. The girls, though, are—presumably from older, promiscuous (and therefore infected) men who are acting as “superspreaders”.

That had been suspected, for sugar daddies are common in South Africa. But viral genetics helps confirm the idea. In theory, they might identify the individuals involved, too—though that would require those people to make themselves available for sampling, which sounds unlikely.

Even with all this attention to detail, though, some budgets will have to go up. A target of having 15m people on ARVs by 2015 was based on clinical guidelines which are now outdated. In 2013 the World Health Organisation decided that people would benefit from taking the drugs earlier in the course of their infections. This added more than 9m to the list. And even knowing whom to give the drugs to requires a lot of work. At the moment, UNAIDS reckons 19m of the 35m estimated to be infected have not been identified. That means they cannot be treated and have no reason to modify their behaviour to avoid infecting other people. Moreover, none of these things, however successful, will truly end AIDS. To do that would mean not just treating, but curing the 35m.

Two years ago, at the 19th AIDS conference, in Washington, DC, there was cautious hope that a cure might be possible. One reason was that a baby girl in the American state of Mississippi had, in a peculiar set of circumstances, been given ARV treatment immediately after birth but the treatment had then been interrupted.

The Mississippi baby’s mother was infected when she gave birth, but her doctors did not know in time to treat her, thereby eliminating the risk of her child picking up the virus at the bloody moment of parturition. The child’s treatment was then interrupted 18 months later, when the mother moved out of the area.

When doctors re-established contact, they found that the child seemed virus-free. If true, she would, in effect, have been cured. They therefore did not give her drugs again, and instead monitored her closely. Sadly, it emerged earlier this month that, 27 months after she had stopped receiving the drugs, the virus had returned.

Studies are nevertheless going on to find out if giving ARVs to adults immediately after infection might stop HIV getting a grip. Dr Lange was setting one up. Even if this approach works, it will be of little use to the 35m already infected. Here, the cupboard looks bare. Another isolated individual, the “Berlin patient” Timothy Brown, has apparently been cured by the drastic step of replacing his bone marrow with a transplant from someone genetically immune to HIV infection. (Mr Brown also had leukaemia; hence the operation.) But that is not an option for most people.

The idea of using genetic engineering to create a similar immunity in laboratory-bred stem cells of the sort that give rise to the cells HIV infects, and then transplanting the result into people, is being investigated. So is the development of drugs which would flush HIV from the places where it hides from the ARVs intended to destroy it. A preliminary result suggesting such flushing might be possible was announced at the conference, but that is a long, long way from an effective medicine.

With luck, one of these options will come good. But until then, the best advice for those infected with HIV is: keep on taking the tablets.